Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32144C43381 for ; Mon, 1 Apr 2019 11:06:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2A5720870 for ; Mon, 1 Apr 2019 11:06:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726415AbfDALGE (ORCPT ); Mon, 1 Apr 2019 07:06:04 -0400 Received: from mail-lf1-f66.google.com ([209.85.167.66]:35193 "EHLO mail-lf1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726167AbfDALGE (ORCPT ); Mon, 1 Apr 2019 07:06:04 -0400 Received: by mail-lf1-f66.google.com with SMTP id u21so5977469lfu.2 for ; Mon, 01 Apr 2019 04:06:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=c3r2m+YCe/wq6frpwAFFoTbrFsSUsOfPgWBlp/6TXCc=; b=Crj+cOxWRbc6COXrYVYZBmBlMRsJbW6iqhdtCo6Yj5TJwqGmG8R6wESBujPDKQi0sz kpBBjNQOTza4TpQhNrZrTNwxUHi5JK0ObP+y2qxvHJb/LsNwi9/G3rfscF4V+EFEo6oJ jR5Zx21wwx7ozxWENHPGzuy//ImOi6bM5GTmNwk1p17zSN91IcxLgBrrrwOUj8kdIr4f AyqYQEstTGH7e7G8TcQubBK81pjU6FjgZy9ISxMmNLET5LM12T3FMMwQiPraFIWWJwzZ 1ZCsBG0wZvHXZs9SpEEQc7x2WMW3VNSfB7UOaZW6iNVf7UQAQPOlkNfhIKW07VciToNe jOlw== X-Gm-Message-State: APjAAAXgS0ZE+/SHNiPiBGsrViX0V2sx8IvRozQrIrySXjQi0PfD00UP 1WW+PiBbCT5hoM292mBpnKiuQw== X-Google-Smtp-Source: APXvYqy7aLhs4fL4enHI65vORzmrJbzhme/e4NHKi5NSdh+2S3CXCEei5i9RuCogHQS57zOn4yUwUA== X-Received: by 2002:a19:5201:: with SMTP id m1mr11332372lfb.68.1554116762068; Mon, 01 Apr 2019 04:06:02 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk (alrua-x1.vpn.toke.dk. [2a00:7660:6da:10::2]) by smtp.gmail.com with ESMTPSA id j9sm2032419lja.92.2019.04.01.04.05.59 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 01 Apr 2019 04:06:01 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 27E7718200F; Mon, 1 Apr 2019 13:05:56 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Erik Stromdahl , kvalo@qca.qualcomm.com, linux-wireless@vger.kernel.org, ath10k@lists.infradead.org Cc: yiboz@codeaurora.org, Erik Stromdahl Subject: Re: [PATCH] ath10k: remove iteration in wake_tx_queue In-Reply-To: <20190327162906.6010-1-erik.stromdahl@gmail.com> References: <20190327162906.6010-1-erik.stromdahl@gmail.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Mon, 01 Apr 2019 13:05:56 +0200 Message-ID: <87bm1qq92j.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Erik Stromdahl writes: > Iterating the TX queue and thereby dequeuing all available packets in the > queue could result in performance penalties on some SMP systems. > > The reason for this is most likely that the per-ac lock (active_txq_lock) > in mac80211 will be held by the CPU iterating the current queue. > > This will lock up other CPUs trying to push new messages on the TX > queue. > > Instead of iterating the queue we fetch just one packet at the time, > resulting in minimal starvation of the other CPUs. Did you test this with Felix' patches reducing the time the lock is held in mac80211? -Toke